18 FRIDTJOF NANSEN. NORw. POL. EXP. 



seen close by (Fig. 2, x), but I now rather think that it was the first begin- 

 ning of the bud-like formation which was further developed later (Figs. 13 — 19). 

 I followed b (Fig. 4) on its wanderings for some time. It moved for- 

 wards by means of the cilium (p) and dragged the tail (h) after itself, exactly 

 in the same way as the organisms in PL V, Fig. 7. It gradually changed 

 its shape (Figs. 4—9). The longish body or nucleus inside, which was at 

 first situated athwart it (Figs. 4 — 6) in the posterior end, gradually took a more 

 longitudinal position (Figs. 7 — 6) and the organism itself became more oblong. 

 At the same time the "nucleus" began to narrow in the middle (Figs. 6 — 7) 

 just as though a division were being prepared, but it came to nothing during 

 the time of observation. At last it became fixed to the glass slide by the 

 tail or stalk (h). The motion which had hitherto been rather rapidly vibrating, 

 now became quieter, and at the same time, the exterior shape of the body be- 

 came more spheroidal (Fig. 10). I observed this stage for a long time, but 

 no changes were seen. At last I had to break off for dinner. When I came 

 back dew had formed on the cover-glass, and when this had been removed 

 I sought in vain for the organism Fig. 10. I then returned to a in Fig. 3, 

 which had remained almost unaltered all the time (Fig. II) 1 . The two cor- 

 puscles or grains in Fig. 3, a had now united into one (Figs. 11, k), and this 

 globule which I called "nucleus", moved slowly towards the end where the 

 stalk adhered (Fig. 12). The bud-like protuberance (d) remained in position 

 but gradually increased in size (Fig. 12). Near the "nucleus" (k) one or 

 sometimes two grains were seen. In the evening (Fig. 13) a drop was being 

 secreted from the cell. The protuberance, d, now gradually increased in size 

 very slowly (Figs. 13 — 19. In fig. 15, the body is turned over so that d is 

 seen on the under side, whilst in Fig. 12, it was on the upper side). In the 

 meantime the "nucleus" underwent several changes. In Fig. 16 it had ejected 

 a grain (x) which moved towards the protuberance, but again returned to 

 the "nucleus" (Fig. 17). In Fig. 17 the "nucleus" was lengthened and con- 

 stricted, and a grain or "nucleolus" was thus given off (Fig. 18, /?. The grain 

 /? is somewhat too small in this figure). After this, two grains were always 



Thie and the following figure (Figs. 11 — 12) are drawn under much greater magnifica- 

 tion (about 1800 diameters, Zeiss F, 4. and long tube) than Figs. 1-10 (Zeiss F, 2; 

 magnified 760 diameters) Fig. 11 was drawn with the aid of the camera lucida. Figs. 

 13—19 were drawn somewhat smaller magnification (Zeiss F, 4, and medium long 

 tube, about 1500 or 1600 diameters), Figs. 13 and 14 with the aid of the camera lucida. 



